The present invention generally relates to a liquid crystal optical switching device and, in particular, relates to such an optical switch including optical fibers that are integrally positioned at a surface proximate the liquid crystal material.
Optical switches are a subject of considerable research and development in light of the recognized advantages of using an optical fiber as a transmission medium in a telecommunications system. To date, most optical switches utilizing liquid crystal material have required precise alignment of an incoming light beam with the liquid crystal surface as well as, a means for collimating the light beam as it leaves an optical fiber.
ln many liquid crystal based devices previously proposed, expensive lenses and numerous optically flat surfaces were required to ensure that an inputted light signal would be incident upon the switching surface of the liquid crystal material at the appropriate critical angle. Such devices have been described in U.S. Pat. No. 4,201,442 issued to McMahon et al. on May 6, 1980, U.S. Pat. No. 4,278,327 issued to McMahon et al. on July 14, 1981 and U.S. Pat. No. 4,385,799 issued to Soref on May 31, 1983. These particular devices are characteristically expensive to manufacture since they require numerous optically flat surfaces to be correctly aligned with each other but also require expensive collimating lens to direct the inputted light beam onto a specific point on the liquid crystal surface. Such devices are not particularly amenable to mass production techniques.
A majority of the problems associated with such optical switching devices have been substantially completely obviated by more recently developed devices such as those discussed and described in U.S. patent application Ser. No. 795,156 and 795,151 entitled LIQUID CRYSTAL OPTICAL SWITCHING DEYICE and LIQUID CRYSTAL OPTICAL SWITCHING DEvICE HAvING MINIMIZED INTERNAL LIGHT PATH respectively, both filed on even date herewith and assigned to the assignee hereof. These patent applications are deemed incorporated herein by reference. Nevertheless, the devices described, although amenable to mass production techniques and requiring fewer optically flat surfaces, still require that the incident light impinge on the liquid crystal material at the appropriate critical angle. The requirement of aligning an optical fiber during the manufacture of the recently developed liquid crystal optical switches is usually accomplished manually and thus incurs time and expense that, if eliminated, would result in a considerable direct cost reduction if eliminated.
Further, whenever light is directed through any medium there is a concern that the light signal will be dispersed or deflected by impurities within that medium. Thus, regardless of the other factors the purity of the transparent medium is always a concern in the fabrication of liquid crystal optical switching devices.
Consequently, the elimination of the critical angle alignment requirement is highly desirous to providing an inexpensive, efficient, liquid crystal optical switching device.